Salaries for Nassau district attorney investigators jumped 40 percent last week, which will cost the county $1.5 million more a year in salaries alone, following a binding arbitration decision.

The agreement also awards about $3 million in retroactive pay, and mandates benefits including extra pay for years of service, clothing and equipment allowances.

The 96-page decision, signed by arbitration panel chairman Martin Scheinman, says the Investigators Police Benevolent Association, whose members formerly were part of the Civil Service Employees Association, should receive salaries and benefits closer to the higher-paid police Detectives' Association.

Nassau's representative on the three-member panel objected, saying the county cannot afford the pay increases. The higher wage scale took effect Thursday and is retroactive to Jan. 1, 2011 -- three months before Nassau's financial control board imposed a freeze on all county wages and annual step increases. As a result, the Nassau Interim Finance Authority has said it has no jurisdiction, and County Attorney John Ciampoli said Nassau must pay.

A spokesman for County Comptroller George Maragos said the retroactive money will be paid later this month or in February.

The panel's decision affects 43 current and former investigators in the office of District Attorney Kathleen Rice, comptroller records show. They had been making an average of $86,400 a year, ranging from about $46,000 to about $109,000. The new wage scale boosts their salary to an average of $121,000, with a low of $98,000 and a high of $190,000.

Some are retired police officers who already receive state pensions, of $56,000 to $106,000 a year, according to data from the Manhattan Institute for Policy Research, a conservative think tank. It was not clear how many are retired New York City police officers because pension officials have refused to disclose the names of retirees receiving pensions and the amount of their benefits.

"There is no dispute members of the bargaining unit come to their positions with extensive experience and the highest of qualifications for their work," the decision says.

"We are convinced the welfare of the public will be best served by awarding a wage package competitive with those enjoyed by persons performing similar duties in comparable jurisdictions."

The decision refers to Suffolk district attorney investigators, who had a higher pay scale.

Suffolk's 2011 payroll shows 44 district attorney's investigators who earned from $71,000 to more than $220,000; at least half were retired police officers, with pensions ranging from $36,000 to $155,000 a year, according to the Manhattan Institute.

Richard Zuckerman, Nassau's representative on the arbitration panel, wrote a partial dissent. Giving the IPBA police benefits "is inconceivable to me . . . while the county remains under NIFA's jurisdiction and in the middle of a severe financial crisis that makes the county's ability to pay for this Award at best doubtful," he wrote.

IPBA president Michael Falzarano did not return several requests for comment. Rice and Maragos declined to comment, and County Executive Edward Mangano couldn't be reached.

Scheinman long has been controversial because of his generous awards to Long Island police unions, whose members are among the highest-paid in the nation.

Complaining that Scheinman used his decisions in one Long Island county to justify even greater benefits in the other, Suffolk lawmakers in 1998 enacted the so-called Scheinman law, which bans the county from using arbitrators who had worked in Nassau during the previous three years. The resolution remains in effect, said Suffolk's legislative counsel, George Nolan.

The arbitrators are chosen from a list of certified arbitrators. The county and the union each get to pick a panel member. They must agree on the third.

Although some Nassau politicians also have complained, Scheinman has continued to handle Nassau police contracts. Scheinman could not be reached for comment.

Nassau's district attorney's investigators separated from the CSEA, whose members earn lower average pay than the police unions, and started their own bargaining unit in 2004. After the county and IPBA could not reach a new contract, they agreed in 2008 to binding arbitration.

The arbitration award sets up a new eight-step wage schedule, effective Jan. 1, 2011, providing annual salaries of $90,608 to $145,826 depending upon years of service.

It covers the period from Dec. 1, 2004, through Dec. 31, 2012.

Nassau District Attorney investigators "assist in basically every aspect" of prosecutions, said Rice spokesman John Byrne. They investigate crimes reported to the office, interview suspects and participate in undercover investigations, he said.

With Paul LaRocco

OTHER BENEFITS AWARDED

In addition to salary increases, an arbitration panel awarded benefits to the Nassau County Investigators Police Benevolent Association, including:

$1,300 a year in clothing allowance

$625 a year for equipment

$500 a year in education incentive if they have earned some college credits

24 days of sick leave a year

27 vacation days annually, increasing to 30 days a year after 16 years in the district attorney's office

Five days of termination pay for every year after 10 service years in the DA's office.

$300 annually for every year of service in the DA's office after reaching the top salary step.

No contribution for health insurance; investigators receive a $2,000 annual payment if they do not take county health insurance

Nassau pays the union $10,000 annually to "better enable" it to "execute its representative role . . . "